Shaft coupling

ABSTRACT

A coupling assembly for a vertical in-line pump and motor combination in which all axial and radial loads are carried by bearings in the motor. The shafts have spaced apart ends and the pump shaft end includes an internal threaded bore. The coupling assembly includes an annular motor shaft hub, an annular pump shaft hub, an adjustment mechanism comprising a threaded shaft to be threaded into the threaded bore in the end of the pump shaft and an adjustment nut secured to an upper end of the threaded shaft, and an annular disc spacer. The components are secured together by axial bolts. Clearance between the pump impeller and its casing is set by rotation of the adjustment nut prior to insertion of the bolts. Completion of the assembly of the coupling establishes the operating clearance for the impeller and the coaxial positioning of the pump shaft to the motor shaft.

This invention relates to a shaft coupling. More particularly, it relates to a shaft coupling to couple a vertical shaft of an in-line pump with the shaft of its associated drive motor.

A typical vertical in-line pump includes a casing positioned in a fluid line. A pump impeller is connected to and rotates with a vertical shaft that extends out of the pump housing through an upper cover. A motor support frame is secured on top of the casing cover surrounding the pump shaft. An electric drive motor with a vertical shaft is supported in coaxial alignment with the pump shaft. A coupling connects the pump motor shaft to the pump shaft. It is made of several separate components. The coupling transfers the power of the motor to the pump shaft to operate the pump.

Typically, the impeller and shaft within the pump casing do not include thrust bearings. The impeller is held in its operative position by the motor shaft thrust bearing. It is therefore necessary to adjust the spacing between the motor shaft and pump shaft to set the operating clearance between the pump impeller and the pump casing. This adjustment is accomplished within the shaft coupling.

Certain in-line pumps include a shaft that is provided with an external thread at the upper end. In such pump-motor combinations a three piece coupling is available. It includes a motor shaft hub and a pump shaft hub connected by axial bolts. An adjustment nut completes the assembly. It is threaded onto the external thread of the free end of the pump shaft and positioned such that when clamped between the motor shaft hub and pump shaft hub it is raised to the appropriate position relative to the motor shaft. This sets the clearance between the pump impeller and casing. Such a coupling is available from John Crane Inc., Morton Grove, Ill.

There are prior known coupling devices suitable for a pump shaft that include an internal threaded bore at the upper or free end. These are of a “clam shell” configuration and clamp onto the motor and pump shaft secured by tangential bolts extending between clam shell halves. Clearance adjustment, by raising the pump shaft is done with the coupling partially assembled onto the shafts and with the disadvantages of the necessity to manually lift the weight of the pump shaft and impeller during assembly and that tightening of the tangential bolts sometimes distorts the coaxial alignment of the two shafts.

An improved form of coupling has been developed for use in pump-motor combinations where the upper end of the pump shaft includes an internal threaded bore. It is comprised of cylindrical components including a pump shaft flange and a motor shaft flange connected by axially extending bolts. It includes an adjustment mechanism with a threaded shaft and adjustment nut component that engages within the internal bore in the pump shaft. It is adjusted without any vertical load on the parts. After proper setting, the axially extending bolts are tightened and the pump shaft and impeller are raised to the appropriate operating clearance. Adjustment disadvantages associated with prior devices for such applications are eliminated. The components are also coaxially aligned with the motor shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a typical vertical in-line pump and motor installation in a fluid line with a known prior art shaft coupling.

FIG. 2 is a sectional plan view, partially broken away on an enlarged scale, of the known prior art coupling illustrated in FIG. 1.

FIG. 3 is a sectional plan view of a shaft coupling embodying the present invention at an intermediate stage of the installation process.

FIG. 4 is a sectional plan view of the shaft coupling of FIG. 3 after installation is complete.

FIG. 5 is a sectional plan view of an alternative embodiment of the shaft coupling of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, there is illustrated a vertical in-line pump assembly generally designated 10 for connecting to a fluid line (not shown). The pump 10 includes a casing 14 that defines the flow passage through the pump. It includes a removable cover 16.

A rotatable impeller 18 is positioned within the casing 14. It is secured to a vertical pump shaft 20. The impeller 18 and pump shaft 20 rotate about a vertical center line on radial bearings located within the motor, and within limiting bushings 21, 22, and 23 within the casing 14 and cover 16. These bushings do not include thrust surfaces. Therefore, unless the impeller and shaft are supported from above, the impeller 18 will rest in contact with the casing. As illustrated in FIG. 1, the impeller 18 defines a support ridge 24 that rests upon an edge of bushing 21 when the impeller 18 and shaft 20 are not supported from above. It should be noted that bushings 21, 22, and 23 do not serve as radial bearings. Axial and radial loads of the rotor of motor 50 and pump impeller 18 are carried by bearings in motor 50.

The pump 10 also includes a seal chamber 26 in which is disposed a mechanical seal 28 that provides a fluid tight seal to prevent leakage along the rotating pump shaft 20. Suitable seals for such installations are available from John Crane Inc., Morton Grove, Ill.

A motor support frame 30 extends vertically up from the cover 16 in surrounding relation to the shaft. It includes a base 32 and two spaced frame members 34 that support a motor mount 36. Pump shaft 20 is secured to the impeller 18 at its lower end. As best seen in FIG. 2, shaft 20 extends out of cover 16 and the seal chamber 26 and terminates in an upper end 40 that includes a reduced diameter portion 42 and a vertical keyway 44. The end 40 of shaft 20 is provided with a threaded internal bore 46 (best seen in FIG. 3).

Motor 50 is secured to, and supported on, mount 36. It provides the power to operate pump 10. Motor 50 includes vertical shaft 52 that may be a different diameter than pump shaft 20. In this embodiment it is somewhat larger than pump shaft reduced diameter portion 42.

Motor shaft 52 is aligned with pump shaft 20. It is provided with a thrust bearing in the motor capable of carrying thrust loads of the pump 10. It also includes radial bearings that receive and carry the radial loads of the motor shaft 52 and also the pump shaft 20.

As shown in FIG. 2, lower end 54 of motor shaft 52 includes a vertical keyway 56 and a surrounding groove 58 closely spaced from the end of the shaft 52.

Prior art coupling assembly 60 operatively connects motor shaft 52 to pump shaft 20. It is arranged to set and maintain the spacing between impeller 18 and casing 14 by adjustment of the distance between the upper end 40 of pump shaft 20 and the lower end 54 of motor shaft 52. This distance is set to provide the requisite operating clearance between impeller 18 and casing 14. This clearance is typically about 0.150 inches.

Coupling assembly includes two clam shell like, axially elongated members 62 that are axially split along facing surfaces 64. These members are removably secured together by tangential bolts 65 which connect with threaded holes 63 in the opposing member.

Each member 62 defines internal, generally semi-cylindrical bore surfaces 66 and 68 in surrounding contact respectively with motor shaft 52 and reduced diameter portion 40 of pump shaft 20. The members 62 are configured such that on tightening of bolts 65 there is a slight gap between facing surfaces 64 when the bore surfaces 66 and 68 are respectively clamped tightly against the motor shaft 52 and the pump shaft 20.

A key 90 is positioned in the keyway 56 in motor shaft 52. A key 92 is positioned in the keyway 44 of pump shaft 20. The keys 90 and 92 extend radially outward of shafts 52 and 20 into appropriate slots (not shown) in one of the axially elongated members 62 to establish a driving relation between motor shaft 52 and coupling assembly 60 and between coupling assembly 60 and pump shaft 20.

The bore surface 66 adapted to contact motor shaft 52 includes an enlarged groove 67 that extends radially outwardly from bore surface 66. The bore surface 68 adapted to contact reduced diameter portion 42 of pump shaft 20 includes an enlarged groove 69 that extends radially outwardly from bore surface 68.

Coupling assembly 60 includes an annular split ring 70. Split ring 70 is sized to fit into both the groove 58 on motor shaft 52 and the groove 67 in elongated members 62. The split ring 70 fixes the axial position of the elongated coupling members 62 relative to the motor shaft 52, and consequently, the pump 10, shaft 20, the casing 14 and casing cover 16.

Coupling assembly 60 additionally includes adjustment, or lift, mechanism 80 that cooperates with the coupling members 62 and pump shaft 20 to raise the pump shaft 20, and attached impeller 18, to provide the appropriate operating clearance between the impeller 18 and casing 14.

The adjustment, or lift, mechanism 80 includes a threaded shaft 82 and a star wheel adjuster 84. Shaft 82 is configured to thread into the internal threaded bore in the upper end 40 of pump shaft 20. Star wheel adjuster 84 is fixed by welding or other means to the upper end of shaft 82. Rotation of star wheel adjuster 84 rotates shaft 82 and causes the star wheel adjuster to move axially relative to the end 40 of the pump shaft 20.

Star wheel adjuster 84 has an outer diameter such that it is received in groove 69 in the surface 68 of axially elongated members 62. It includes a bottom radial surface 85 that rests on the bottom radial surface of groove 69 and transfers vertical load received from pump shaft 20 through threaded shaft 82 to the elongated coupling members 62. Assembly and adjustment of the coupling proceeds in a variety of sequences. In each, however, it is necessary to handle the coupling members 62 separately or loosely held together. It is also necessary to lift the weight of the pump shaft 20 and impeller 18 during the assembly process.

Completion of the process results in the establishment of a driving relation between motor shaft 52 and pump shaft 20 with the requisite clearance established between impeller 18 and casing 14. The adjustment mechanism 80 is manipulated to rotate threaded shaft 82 within the threaded bore in the end 40 of shaft 20 to set the appropriate distance between support ridge 24 of the impeller to the upper face of the associated bushing 21.

The split ring 70 within groove 67 in surface 66 of axially elongated member 62 fixes the distance of the groove 69 in surface 68 relative to the lower end 54 of motor shaft 52. To establish the impeller operating clearance, it is necessary to position the bottom radial surface of star wheel adjuster against the bottom radial surface of groove 69 and also have the star wheel adjuster positioned relative to the end 40 of pump shaft 20 such that the pump shaft 20 is lifted sufficiently to create the operating clearance.

As is evident, the adjustment of the coupling of the prior art must be accomplished while only one axially elongated member 62 is loosely in place against the motor shaft 52 and pump shaft 20. At the same time, star wheel adjuster 84 must be rotated within the groove 69 to its correct position relative to pump shaft 20. These efforts are difficult and include lifting the weight of the impeller 18 and pump shaft 20 during the assembly process.

The coupling assembly of the present invention eliminates the enumerated difficulties in installation and adjustment of the coupling. The coupling assembly, generally designated 160, is illustrated in FIGS. 3 and 4.

Coupling assembly 160 is intended for application in a vertical in-line pump arrangement, as already described. It is suitable for pump shaft arrangements that include an upper end having an internal threaded bore. The various elements of the pump 10 and motor 50 are as previously described and details may be understood from FIGS. 1 and 2 and the associated written description. These include, without limitation, the configuration of the shafts 20 and 52, the keys 90 and 92 and split ring 70.

Referring to FIG. 3, coupling assembly 160 includes separate components including an annular motor shaft hub 162, split ring 70 and an annular pump shaft hub 163. It also includes an adjustment mechanism 180 comprising an annular adjustment nut 184 and threaded shaft 182. The assembly also includes annular disc spacer 186.

The coupling assembly components are secured together by axially elongated bolts 165 with self-locking nuts 159 in threaded engagement with the threaded ends of the bolts. These bolts operatively couple motor shaft hub 162, pump shaft hub 163, adjustment nut 184 and disc spacer 186 in an assembled relation. As illustrated in FIG. 3, bolts 165 are sufficiently long to permit assembly of the components of coupling 160 onto the motor shaft 52 and pump shaft 20 with the support ridge 24 of impeller 18 resting on the end of bushing 21 within casing 14. That is, the coupling elements can be connected together with bolts 165 and nuts 159 with no clearance between impeller 18 and casing 14. As will be explained and as illustrated in FIG. 4, after the coupling is adjusted and fully assembled, the bolts and nuts are threaded together to raise the impeller 18 the amount of the clearance needed to place it in its operational relationship with casing 14. Tightening the bolts and nuts also establishes the coaxial positioning of the pump shaft 20 to motor shaft 50. It should be mentioned, that, rather than employing separate nuts such as nuts 159 on bolts 165, the motor shaft hub 162 or the pump shaft hub 163 could be provided with threaded holes to receive and lock with bolts 165.

All major components are annular and are made of metal, preferably steel or stainless steel. Each includes a plurality of bolt holes formed in a common hole spacing pattern and bolt circle diameter. The number of bolt holes, usually equally spaced, about the bolt circle depends on the size of the pump and its power requirement. This number could range from four to as many as fourteen.

Annular motor shaft hub 162 includes radial bolt flange 171 with bolt holes on a common hole spacing pattern and bolt circle diameter as described above. Hub 162 includes an inner bore 161 that receives motor shaft 52 in a slidable but close fitting coaxial relation. It includes a vertical keyway 166 that receives key 90 positioned in keyway 56 of motor shaft 52. Thus hub 162 is connected to rotate with the motor shaft 52 and transfers rotational force from the motor shaft 52 to the coupling assembly 160.

The internal bore 161 in motor shaft hub 162 is provided with a counter bore 167 having a cylindrical surface 173 sized to fit about the outer diameter of split ring 70. It also forms shoulder 172. Hub 162 defines a planar downwardly facing annular surface 164 that extends radially from counter bore 167.

Contact of shoulder 172 of counter bore 167 with the upper radial surface of split ring 70 fixes the vertical position of hub 162 relative to motor shaft 52. The ring 70 is retained within the groove 58 of motor shaft 52 by the outer cylindrical surface 173 of the counter bore 167. The contact of shoulder 172 of counter bore 167 with the upper surface of split ring 70 determines the vertical location of planar downwardly facing annular surface 164.

Annular pump shaft hub 163 includes a radial bolt flange 174 with bolt holes on a common hole spacing pattern and bolt circle diameter as previously described. The flange 174 has the same outer diameter as bolt flange 171 of motor shaft hub 162. Hub 163 defines a planar upwardly facing annular surface 169. An upwardly directed pilot protrusion 176 extends upwardly from surface 169. It has about the same diameter as the counter bore 167 in motor shaft hub 162.

A central bore 168 is sized to receive the outer surface of reduced diameter area 42 of pump shaft 20 in a close fitting coaxial relation but such that hub 163 can slide axially. Hub 163 includes an internal keyway 175 that receives key 92 in keyway 44 of pump shaft 20. Hub 163, therefore, is fixed to rotate pump shaft 20 in a driving relation.

Adjustment or lift mechanism 180 includes threaded shaft 182 and adjustment nut 184 secured to it at its upper end by welding or other fixing method. For example, an adhesive such as Loctite® would be employed between the upper end of shaft 182 and adjustment nut 184. (Loctite is a registered trademark of Henkel Corporation, Gulph Mills, Pa.)

Shaft 182 is provided with threads that thread into the internal threaded bore 46 in the upper end 40 of pump shaft 20. Adjustment nut 184 is annular and is positioned above the pump shaft hub 163 with the threaded shaft 182 extending through the hub 163 and threaded into the bore at the end 40 of pump shaft 20. It is of the same outer diameter as motor shaft hub 162 and pump shaft hub 163. It also includes bolt holes as described above on the same hole spacing pattern and bolt circle diameter as the bolt holes in the hubs.

Adjustment nut 184 includes a planar downward facing annular surface 193 facing adjacent, planar upwardly facing annular surface 169 of pump shaft hub 163 and provided with a counter bore 194 that is sized to receive the pilot protrusion 176 of pump shaft hub 163. The tolerances between the outer cylindrical surface of pilot protrusion 176 and counter bore 194 is close and intended to maintain these components in a coaxial relation.

Rotation of adjustment nut 184 causes threaded shaft 182 to move vertically relative to threaded bore 46 of upper end 40 of pump shaft 20. This causes adjustment, in the vertical direction, of the axial position of adjustment nut 184 relative to the end 40 of pump shaft 20.

Adjustment nut 184 also includes planar upwardly facing annular surface 195 which includes an upward facing annular pilot protrusion 196 with an outer diameter about the same as pilot protrusion 176 on pump shaft hub 163. Nut 184 has an axial thickness about the same as the axial thickness of each of the motor shaft hub 162 and pump shaft hub 163.

The final component of the coupling assembly 160 is disc spacer 186. It is annular with bolt holes on the common hole spacing pattern and bolt circle diameter, as discussed, that align with the bolt holes of the other coupling components. The spacer 186 has the same outer diameter as the adjustment nut 184 and the motor shaft hub 166 and pump shaft hub 167. It includes a planar upward facing annular surface 197 that faces adjacent, planar downwardly facing annular surface 164 of motor shaft hub 162. It includes an upwardly facing pilot protrusion 198 sized to fit within counter bore 167 in motor shaft hub 162. The tolerance between the outer cylindrical surface of upwardly facing pilot protrusion 198 and counter bore 167 in motor shaft hub 162 is close and intended to maintain these components in a coaxial relation. Disc spacer 186 includes a planar downwardly facing annular surface 200 that faces adjacent, planar upwardly facing annular surface 195 of adjustment nut 184. Surface 200 includes a counter bore 201 sized to receive the pilot protrusion 196 of adjustment nut 184. The tolerances between the outer cylindrical surface of pilot protrusion 196 and counter bore 201 is close and intended to maintain these components in a coaxial relationship.

Disc spacer 186 has an axial length that defines the assembled distance between the planar downwardly facing annular surface 164 of motor shaft hub 162 and the planar upwardly facing annular surface 195 of adjustment nut 184. The axial length of disc spacer 186 depends on the distance between the downward end of the motor shaft 52 and the upper end 40 of the pump shaft 20 in any given application.

Assembly and adjustment of the coupling assembly 160 is less complex than the prior art device of FIGS. 1 and 2. Most significantly, adjustment is achieved without the necessity to lift the weight of the pump shaft 20 and impeller 18. Also, tightening the axial bolts will not affect the coaxial alignment of pump shaft 20 and motor shaft 52.

The first steps in the assembly process are to place the motor shaft hub 162 and pump shaft hub 163 upon motor shaft 52 and the reduced diameter portion 42 of pump shaft 20. With keys 90 and 92 in place the hubs are fixed for rotation with the shafts.

The vertical position of motor shaft hub 162 is established by sliding the hub upward, installing split ring 70 and then sliding hub 162 downward until the ring 70 rests against shoulder 172 of counter bore 167.

Adjustment mechanism 180 is secured to the end 40 of pump shaft 20. Threaded shaft 182 is threaded completely into the threaded bore 46 in the end 40 of pump shaft 20 using adjustment nut 184. The disc spacer 186 is then positioned upon the planar upwardly facing annular surface 195 of adjustment nut 184 with pilot protrusion 196 positioned in counter bore 201 of disc spacer 186. Threaded shaft 182 is then rotated to a position where the distance between the planar upwardly facing annular surface 197 of disc spacer 186 is spaced from planar downwardly facing annular surface 164 of motor shaft hub 162, by the amount of the intended clearance between support ridge 24 of impeller 18 and bushing 21 of casing 14. This clearance amount is usually about 0.150 inches.

Pump shaft hub 163 is slid upwardly such that planar upwardly facing annular surface 169 of pump shaft hub 163 is in facing relation to planar downwardly facing annular surface 193 of adjustment nut 184 with pilot protrusion 176 of pump shaft hub 163 in counter bore 194 of adjustment nut 184. At this juncture, the only space between components is the gap between planar downwardly facing annular surface 164 of motor shaft hub 162 and planar upwardly facing annular surface 197 of disc spacer 186. The components are positioned to align the bolt holes and the bolts 165 are inserted. Nuts 159 are then placed on the ends of the bolts and the ring of bolts tightened to draw the components together axially. When completely tightened, pump shaft hub 163, the adjustment nut 184, and disc spacer 186 are raised until the planar upwardly facing annular surface 197 of disc spacer 186 comes into contact with planar downwardly facing annular surface 164 of motor shaft hub 162. Motor shaft hub 162 cannot move downwardly because of contact of shoulder 172 with split ring 70.

As the nuts 159 are tightened, planar upwardly facing annular surface 169 of pump shaft hub 163 contacts planar downwardly facing annular surface 193 of adjustment nut 184. Continued tightening raises adjustment nut 184, threaded shaft 182 and consequently pump shaft 20 until the set clearance between the planar downwardly facing annular surface 197 of disc spacer 186 and adjacent, planar downwardly facing annular surface 164 of motor shaft hub 162 is eliminated. When so positioned the pump shaft 20 has been raised by the amount of clearance necessary to operate impeller 18 within casing 14 completing the assembly process.

When so assembled, pilot protrusion 176 of pump shaft hub 163, pilot protrusion 196 of adjustment nut 184 and pilot protrusion 198 of disc spacer 186, reside respectively in counter bore 194 of adjustment nut 184, counter bore 201 of disc spacer 186, and counter bore 167 of motor shaft hub 162. This relationship establishes and maintains the coaxial relationship between the coupling components. To ensure coaxial alignment of the coupling components, the radial clearance between the protrusions and associated counter bores is between 0.001 inches and 0.002 inches measured on the diameters. Each protrusion is provided with a chamfer to aid in interfitting the protrusions into the counter bores.

Also, the axial length of the protrusions are slightly less than the intended operating clearance between the pump impeller and casing. Protrusion 198 is sized such that when nuts 159 are tightened on bolts 165, the top planar surface of protrusion 198 is closely spaced to the lower end 54 of motor shaft 52. The clearance is in the range of 0.010 to 0.016 inches. This relationship provides a limit or stop to prevent excessive upward movement of the pump shaft 20 and impeller 18 in the event upward thrust forces exist within pump 10.

It should be noted that optionally, the pilot protrusions, such as pilot protrusion 196 of adjustment nut 184, and pilot protrusion 198 of disc spacer 186 could extend axially downwardly rather than axially upwardly and engage counter bores formed respectively in pump shaft hub 163 and adjustment nut 184. Motor shaft hub 162 would include a downwardly facing pilot protrusion that would engage an appropriate counter bore in planar upwardly facing annular surface 197 of disc spacer 186.

Another option contemplated is that the pilot protrusions and associated counter bores need not be circular. Also other alignment mechanisms could be employed, such as dowel pins set in one component and received in appropriately sized holes in the other.

The coupling assembly 160 provides a connection that can be implemented without disturbing the existing relationship of the pump shaft 20 and motor shaft 52. To remove the motor 50, for example, to insert a coupling assembly, requires that realignment procedures be employed to reset the coaxial relationship when motor 50 is reset in place on frame 30. In addition, motors such as employed to power pumps 10 are very heavy and difficult to handle.

To utilize the coupling assembly 160 it is necessary to install the threaded shaft 182 into the internal thread in the upper end 40 of pump shaft 20. To do so, the axial length of the threaded shaft 182 and attached adjustment nut 184 must be less than the distance between the lower end of motor shaft 52 and upper end 40 of pump shaft 20.

It is then necessary to thread the threaded shaft 182 substantially into the internal threaded bore in the end of the pump shaft 40. Doing so causes the planar upwardly facing annular surface 195 of adjustment nut 184 to move downward a substantial distance from the planar downwardly facing annular surface 164 of motor hub 162. Since tightening of the axial bolts 165 and nuts 159 moves the adjustment nut 184 upward only a distance equal to the intended operating clearance between the impeller 18 and its casing 14, the remaining gap must be filled by disc spacer 186. Thus, the axial height of disc spacer 186 is dictated by the distance between the planar upwardly facing annular surface 195 of adjustment nut 184 and planar downwardly facing annular surface 164 of motor shaft hub 162 when shoulder 172 of motor hub 162 rests on split ring 70 at the bottom of counter bore 167 and adjustment nut 184 is adjusted to its assembled axial position relative to the upper end 40 of pump shaft 20.

Another advantage derived from the coupling assembly 160 of the present invention is that when it is assembled between motor shaft 52 and pump shaft 20, bolts 165 prevent rotation of adjustment nut 184 relative to pump shaft 20. Thus there can be no change in the clearance distance set prior to insertion of the bolts 165 through the bolt holes in the coupling components.

An alternative embodiment of the invention is illustrated in FIG. 5. It is useful in applications with minimal vertical clearance between the motor mount 36 and seal chamber 26. The coupling assembly of this embodiment, includes a motor shaft hub 162, pump shaft hub 163, adjustment mechanism 180, with adjustment nut 184 and threaded shaft 182 which are the same as the embodiment of FIGS. 3 and 4. These components assemble and adjust as described in the previous embodiment. However, a disc spacer 286 is provided with threaded holes at the bolt circle. Downwardly extending threaded bolts 265A extend through the bolt holes in motor shaft hub 162. Upwardly extending bolts 265B extend through bolt holes in pump shaft hub 163 and adjustment nut 164. The bolts 265A and 265B thread into, and lock with the threaded holes in disc spacer 286. Tightening the bolts causes the adjacent protrusions and counter bores to coaxially align the components relative to the motor shaft 52. Also, the pump shaft 20 and impeller 18 is raised upward to amount of the clearance to be provided between impeller 18 and its casing 14.

Various features of the present invention have been described with respect to a specific embodiment thereof. It must be understood that various changes and modifications may be made by one skilled in the art without departing from the scope of the invention and it is intended and contemplated that the invention encompass such changes and modifications as fall within the scope of the appended claims. 

1. A motor shaft to pump shaft coupling assembly comprising: an annular motor shaft hub for attachment to a motor shaft; an annular pump shaft hub for attachment to a pump shaft; an adjustment mechanism comprising a threaded shaft for threaded connection to a pump shaft having an internal threaded bore and an annular adjustment nut secured to an end of said shaft; an annular disc spacer for disposition between said motor shaft hub and said adjustment mechanism.
 2. A motor shaft to pump shaft coupling assembly as claimed in claim 1 wherein said motor shaft hub is configured to be placed in driving relation with a shaft of a motor and said pump shaft hub is configured to be placed in a driving relation with a shaft of a pump, said components each include holes on a common hole spacing pattern, and bolt circle diameter, said assembly further includes bolts to secure said coupling components together.
 3. A motor shaft to pump shaft coupling assembly as claimed in claim 2 wherein said motor shaft hub and pump shaft hub are configured to be axially slidable relative to the respective motor shaft and pump shaft and said bolts are adapted to extend through said holes in said components and said assembly further includes nuts adapted to thread onto said bolts.
 4. A motor shaft to pump shaft coupling assembly as claimed in claim 3 wherein said assembly further includes a split ring, said motor shaft hub includes a counter bore defining a shoulder to receive said split ring in contact with said shoulder to fix the axial position of said motor shaft hub on a motor shaft.
 5. A motor shaft to pump shaft coupling assembly as claimed in claim 4 wherein said motor shaft hub includes a planar downwardly facing annular surface extending radially from said counter bore, said pump shaft hub includes a planar upwardly facing annular surface, said adjustment nut includes a planar downwardly facing annular surface adjacent, and facing said planar upwardly facing annular surface of said pump shaft hub and a planar upwardly facing annular surface, said disc spacer includes a planar downwardly facing annular surface adjacent and facing said planar upwardly facing annular surface of said adjustment nut, said disc spacer further includes planar upwardly facing annular surface adjacent and facing said planar downwardly facing annular surface of said motor shaft hub.
 6. A motor shaft to pump shaft coupling assembly as claimed in claim 5 wherein one of each said adjacent planar facing annular surfaces includes a pilot protrusion and the other adjacent planar facing annular surface includes a counter bore to receive said pilot protrusion.
 7. A motor shaft to pump shaft coupling assembly as claimed in claim 6 wherein said pilot protrusions in said one of said surfaces are coaxial with said counter bores in the other of said adjacent planar facing annular surfaces.
 8. A motor shaft to pump shaft coupling assembly as claimed in claim 7 wherein said bolts secure said components together with facing planar upwardly facing annular surfaces and planar downwardly facing annular surfaces in contact with each other and said pilot protrusions received in said counter bores.
 9. A motor shaft to pump shaft coupling assembly as claimed in claim 8 wherein said bolts are sufficiently long to connect said components together, when said planar upwardly facing annular surface of said adjustment nut is spaced from said planar downwardly facing annular surface of said motor shaft hub a distance equal to the axial length of said disc spacer plus an amount equal to the clearance to be established between a pump impeller and its casing.
 10. A motor shaft to pump shaft coupling assembly as claimed in claim 9 wherein said bolts include self-locking nuts and movement of said nuts onto said bolts draws said coupling assembly components together.
 11. A motor shaft to pump shaft coupling assembly as claimed in claim 10 wherein the axial height of each said protrusion is less than the amount of said clearance to be established between the associated pump impeller and its casing.
 12. A motor shaft to pump shaft coupling assembly as claimed in claim 5 wherein said threaded shaft of said adjustment mechanism received into the threaded internal bore of a pump shaft end and said distance between said planar upwardly facing annular surface of said adjustment nut and said planar downwardly facing annular surface of said motor hub is adjusted by rotation of said adjustment nut and threaded shaft relative to the pump shaft.
 13. A motor shaft to pump shaft coupling assembly as claimed in claim 1 wherein said pump shaft hub includes a planar upwardly facing annular surface having an upwardly directed pilot protrusion, said adjustment nut includes a planar downwardly facing annular surface having a counter bore sized to receive said pilot protrusion on said pump shaft hub, said adjustment nut includes a planar upwardly facing annular surface having an upwardly directed pilot protrusion, said disc spacer includes a planar downwardly facing annular surface having a counter bore sized to receive said pilot protrusion on said adjustment nut, said disc spacer includes a planar upwardly facing annular surface having an upwardly directed pilot protrusion, and said counter bore in said motor shaft hub is sized to receive said upwardly directed pilot protrusion on said disc spacer.
 14. A motor shaft to pump shaft coupling assembly as claimed in claim 13 wherein said motor shaft hub is configured to be placed in driving relation with a shaft of a motor and said pump shaft hub is configured to be placed in a driving relation with a shaft of a pump, said components each include holes on a common hole spacing pattern, and said assembly further includes bolts to secure said coupling components together.
 15. A motor shaft to pump shaft coupling assembly as claimed in claim 14 wherein said motor shaft hub and pump shaft hub are configured to be axially slidable relative to the respective motor shaft and pump shaft and said bolts are adapted to extend through said holes in said components and said assembly further includes nuts adapted to thread onto said bolts.
 16. A motor shaft to pump shaft coupling assembly as claimed in claim 15 wherein said assembly further includes a split ring, said motor shaft hub includes a counter bore defining a shoulder to receive said split ring in contact with said shoulder to fix the axial position of said motor shaft hub on a motor shaft.
 17. A motor shaft to pump shaft coupling assembly as claimed in claim 13 wherein said pilot protrusions are coaxial with said counter bores.
 18. A motor shaft to pump shaft coupling assembly as claimed in claim 14 wherein said assembly includes bolts to secure said components together with facing planar upwardly facing annular surfaces and planar downwardly facing annular surfaces in contact with each other and said pilot protrusions received in said counter bores.
 19. A motor shaft to pump shaft coupling assembly as claimed in claim 18 wherein said bolts are sufficiently long to connect said components together, when said planar upwardly facing annular surface of said adjustment nut is spaced from said planar downwardly facing annular surface of said motor shaft hub a distance equal to the axial length of said disc spacer plus an amount equal to the clearance to be established between a pump impeller and its casing.
 20. A motor shaft to pump shaft coupling assembly as claimed in claim 19 wherein said assembly includes self-locking nuts and movement of said nuts onto said bolts draws said coupling assembly components together.
 21. A motor shaft to pump shaft coupling assembly as claimed in claim 20 wherein the axial height of each said protrusions is less than the amount of said clearance to be established between the associated pump impeller and its casing.
 22. A motor shaft to pump shaft coupling assembly as claimed in claim 13 wherein said threaded shaft of said adjustment mechanism is received into the threaded internal bore of a pump shaft end and said distance between said planar upwardly facing annular surface of said adjustment nut and said planar downwardly facing annular surface of said motor hub is adjusted by rotation of said adjustment nut and threaded shaft relative to the pump shaft.
 23. A motor shaft to pump shaft coupling as claimed in claim 2, wherein said annular disc spacer includes threaded holes, and said bolts comprise bolts to extend through said motor shaft hub, and separate bolts to extend through said pump shaft hub and adjustment nut, said bolts adapted for threaded engagement to said disc spacer.
 24. A motor shaft to pump shaft coupling as claimed in claim 5, wherein said annular disc spacer includes threaded holes, and said bolts comprise bolts to extend through said motor shaft hub, and separate bolts to extend through said pump shaft hub and adjustment nut, said bolts adapted to be connected to said disc spacer.
 25. A motor shaft to pump shaft coupling as claimed in claim 12, wherein said annular disc spacer includes threaded holes, and said bolts comprise bolts to extend through said motor shaft hub, and separate bolts to extend through said pump shaft hub and adjustment nut, said bolts adapted to be connected to said disc spacer.
 26. A motor shaft to pump shaft coupling as claimed in claim 18, wherein said annular disc spacer includes threaded holes, and said bolts comprise bolts to extend through said motor shaft hub, and separate bolts to extend through said pump shaft hub and adjustment nut, said bolts adapted to be connected to said disc spacer.
 27. A motor shaft to pump shaft coupling as claimed in claim 22, wherein said annular disc spacer includes threaded holes, and said bolts comprise bolts to extend through said motor shaft hub, and separate bolts to extend through said pump shaft hub and adjustment nut, said bolts adapted to be connected to said disc spacer. 